I just registered.
Need to complete survey to get the $500.
At the end of survey completion, guess what.
The $500 will be used to cover the exchange fees.
Means you can't withdraw it and you need to actively exchange to enjoy the free exchange fees up to $500.
Still not sure exactly how it works.
Read my first posting again:
"... you will get a 500$ bonus on your trading fees"
...of course nobody will give you 500$ just for a simple registration, that's just stupid.
Anyways, in my opinion the $500 bonus is awesome